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  1. #31
    Jeff Bannow's Avatar
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    This has been an amazingly useful thread.
    - Jeff (& sometimes Eva, too) - http://www.jeffbannow.com

  2. #32

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    Many thanks PE for yet another invaluable darkroom chemistry tutorial. Nearly fifty years ago as a student I practiced a similar sulfuric acid/carbonate (acid/base) regimen in cleaning our student chemistry labs' glassware.
    I still remember the vivid professorial safety demonstrations during the first week of classes surrounding the addition of H2SO4 to water in glassware, or the addition of metallic sodium to H2O in a lab sink. Thanks again.

  3. #33
    Photo Engineer's Avatar
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    In our lab, a student got H2SO4 on her lab coat and told no one. It dissolved her coat, her clothes and started on her before the other instructor got her into the sink and had started running water on her abdomen. In another incident a student poured benzene with Sodium shavings down the sink and then washed it down with water causing a flame clear to the ceiling along with a beautiful "bang".

    Oh, the stories are long and painful. We even had our explosions and fires at EK with TOTL professionals. You cannot be too careful in a chemistry lab.

    Thanks for your interest.

    PE

  4. #34
    TheFlyingCamera's Avatar
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    Is the leftover hardener from Kodak Rapid Fixer sufficiently weak to be safe yet sufficiently strong to be effective as a cleaning agent? I've got lots of bottles of the stuff sitting left over, as I don't use the hardener for prints or films anymore.

  5. #35
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    My mum was a lab washer many years ago, doing the cleaning up work in an Paediatric Oncology Research lab at Melbourne's Royal Children's Hospital. Detergent, antiseptic and steam wash/dry (autoclave) then sterile repackaging was the stock standard treatment for all glasswear, from tiny, frail pipettes to huge bulbous vessels that mixed and separated autologous bone marrow for transplants (something to do with horses to humans). All the poisonous, fancy chemical concoction stuff mentioned above is overly extravagant and unnecessary — you will get more contaminants from tap water than what is on glass, and it's just for darkroom use. Bicarb soda and hot water and scrubbing is all that is needed. Unless you're in surgery, you won't be needing an autoclave.
    .::Gary Rowan Higgins

    A comfort zone is a wonderful place. But nothing ever grows there.
    —Anon.






  6. #36
    OldBikerPete's Avatar
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    I'm another ex chemist and we used PE's methods up to about 15 years ago.
    More recently we switched to one of the extremely aggressive detergents that had become available -I don't remember the name (hey, I've been retired a while) 'something-100'. Contact lab suppliers to find out. I'm sure that if there was some really stubborn deposit on some glassware I'd still revert to chromic acid.

  7. #37
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    Quote Originally Posted by TheFlyingCamera View Post
    Is the leftover hardener from Kodak Rapid Fixer sufficiently weak to be safe yet sufficiently strong to be effective as a cleaning agent? I've got lots of bottles of the stuff sitting left over, as I don't use the hardener for prints or films anymore.
    The acid content is good, but the aluminum would make a mess if you hit it with alkali. You would get an aluminum scum.

    PE

  8. #38

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    Quote Originally Posted by lajolla View Post
    I still remember the vivid professorial safety demonstrations during the first week of classes surrounding the addition of H2SO4 to water in glassware
    The only thing I remember from high school chemistry class (a very long time ago) is that one NEVER adds water to an acid, always acid to water, to prevent bad things from happening. Don't remember the details of the possible reactions, but the teacher said to always remember it this way: Acid > Water is Aw Wight

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